4-Antenna Precoding Matrix Codebook Design for MIMO Feedback
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Solution Overview
Problem
The 3GPP LTE system's 4-antenna codebook design for precoding matrices is limited by the need for precise space quantization, leading to performance deterioration in multi-user MIMO scenarios due to limited codebook size and feedback capacity, especially when subsampling is applied, resulting in fewer applicable precoding matrices for uniform linear array antennas.
Innovation Solution
The method involves determining a 4-antenna precoding matrix using a codebook structure where the precoding matrices are represented by a first and second codebook index, allowing for more precoding matrices to be indicated without changing the feedback mode or bits, ensuring performance for both uniform linear array and dual-polarized antennas by using a specific set of DFT vectors and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If codebook subsampling is applied to reduce feedback overhead, then feedback capacity is reduced, but the number of applicable precoding matrices for uniform linear array antennas decreases, leading to performance deterioration
Solution Approach 1:
The patent introduces a two-stage codebook structure with first and second codebook indices, effectively adding a dimensional layer to the codebook selection process. This allows the system to maintain a larger effective codebook size for ULA antennas while keeping feedback overhead constrained, as the dual-index mechanism provides finer granularity in precoding matrix selection without proportionally increasing feedback burden.
Solution Approach 2:
The patent applies different codebook design strategies to different antenna configurations. Specifically, it optimizes the codebook structure locally for uniform linear array antennas by using DFT-based precoding matrices, while maintaining separate optimization for dual-polarized antennas. This localized optimization ensures that each antenna type receives tailored codebook design that maximizes its specific performance characteristics.
2Device complexity
If a single codebook is used for 4-antenna system, then codebook design is simple, but space quantization precision is limited, affecting MU-MIMO performance
Solution Approach 1:
The patent segments the codebook into multiple groups, each optimized for specific antenna configurations and transmission scenarios. By dividing the codebook into distinct segments with specialized designs, the system achieves higher quantization precision for different MIMO modes without requiring a single overly complex unified codebook structure.
Solution Approach 2:
The patent designs a universal codebook framework that serves multiple functions: it supports both single-user and multi-user MIMO, accommodates different antenna configurations (ULA and dual-polarized), and provides appropriate precoding matrices for various rank indicators. This multi-functional codebook structure achieves high precision across diverse scenarios while maintaining reasonable design complexity.
3Measurement precision
If codebook size is increased to improve quantization precision, then feedback overhead increases, but feedback channel capacity is limited
Solution Approach 1:
The patent implements dynamic codebook selection based on channel conditions, antenna configuration, and transmission mode. The system dynamically adapts which codebook group and specific precoding matrix to use, allowing high precision when needed while minimizing feedback overhead in other scenarios. This dynamic approach optimizes the trade-off between precision and overhead in real-time.
Solution Approach 2:
The patent changes key parameters of the codebook structure, including the use of DFT-based matrices with specific phase differences, adjustable codebook grouping, and flexible rank indicator mappings. These parameter changes enable the system to achieve high quantization precision through structured mathematical designs rather than simply increasing codebook size, thereby reducing feedback overhead.
Data Source
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AI summary
The present invention discloses a method for transmitting a 4-antenna precoding matrix, a user equipment, and a base station. The method includes: determining a rank used for indicating the number of transmission layers; determining a first precoding matrix in a codebook set corresponding to the rank; determining a first PMI and a second PMI used for indicating the first precoding matrix; and sending the first PMI and the second PMI used for indicating the first precoding matrix to a base station. By means of the method for transmitting a 4-antenna precoding matrix, the user equipment, and the base station according to embodiments of the present invention, more precoding matrices that are applicable to a uniform linear array antenna may be indicated without changing a feedback mode or feedback bits, and it may be ensured that performance for application of a dual-polarized antenna is not affected, so that system performance may be improved and user experience may be enhanced.